Sometimes football matches do not last 90 minutes. Sometimes they do not even last 19. Any idea this was a contest ended when David Silva scored Manchester City’s third goal in the 18th minute.

Yet if an early onslaught served as a devastating demonstration of City’s calibre, what followed still had a certain significance.

Pep Guardiola’s team scored six times for the second occasion this season, to add to their two five-goal hauls. Two of those six were scored by Raheem Sterling, two more assisted by him, a further one involved him.

As City displaced the winger’s former employers Liverpool from the summit, there were regular choruses of “Raheem Sterling, he’s top of the league”. More than most, Sterling has taken them there.

“He is in incredible form,” Guardiola said. “He is sharp, fast, clever, fighting, decisive. The first season [of his reign] he was scared. I have the feeling he is now enjoying scoring goals and making assists.”

The numbers indicate as much. No one has been involved in more Premier League goals this campaign. There was already ample evidence of why Sterling merits the new contract that should soon be announced, but he produced plenty more. He has allied ruthlessness with relentlessness in a way he did not before Guardiola’s appointment, speed, style and statistics in a manner that makes him an embodiment of City.

He is not alone in that. Sergio Aguero brought up his 150th Premier League goal, though it seemed to please Guardiola more than he set up each of Sterling’s double.

His first, on the stroke of half-time, was finished at the second attempt after Aguero robbed a dozing Cedric Soares, who summed up how Southampton were off the pace. His second was rifled in after a defence-splitting pass from the Argentine.

He was returning a favour. Sterling wriggled his way to the byline to supply Aguero for a tap-in for his latest landmark and City’s second goal. Yet it was a match when the champions boasted searing speed and incision on both flanks.

Leroy Sane bookended the game with telling contributions, completing the scoring from Sterling’s pass and breaking the deadlock when his low cross was inadvertently finished by Southampton defender Wesley Hoedt.

When Silva hooked in the third, after Sterling’s cross was flicked on by Sane, City had secured victory with 80 per cent of the match remaining. Rampant and inventive, clinical and creative, they were sharper and hungrier than Southampton.

“That was the game gone,” said Mark Hughes, whose sides have conceded 13 goals on his last two trips to the Etihad Stadium. “The gameplan you want to implement goes out of the window. We weren’t strong enough in that opening period."

They were distinctly fallible thereafter. Sane rattled the post and Guardiola said: “We could have scored eight or nine.” Yet Hughes was not alone in rueing defensive generosity. “We were not stable behind,” said Guardiola.

Perhaps the day’s greatest surprise was that City conceded for the first time in seven league matches and Southampton scored for the first in six.

Danny Ings, who converted a penalty he won, became the only opposing striker or midfielder to muster a top-flight goal against City this season. His side could have scored more.

“When you concede those situations in the next stage of Champions League, you are out because the level is higher,” said Guardiola. “We can improve.” Southampton need to.